1. Field of the Invention
The present invention relates to a method for manufacturing an MIM (metal filmxe2x80x94insulating filmxe2x80x94metal film) capacitor structure and to a method for manufacturing an MIM capacitor element, and more particularly to a method for forming an MIM capacitor structure on a semiconductor wafer provided with an integrated circuit.
2. Description of the Related Art
The following techniques are used to form MIM capacitor structures on semiconductor wafers provided with integrated circuits.
Specifically, there are methods in which a bottom electrode film (for example, an AlCu film) is formed by sputtering on a semiconductor wafer, an insulating film (for example, an SiON film) is formed by CVD thereon, and a top electrode film (for example, a TiN film) is formed by sputtering on the insulating film.
Sputtering is a method in which inert gas ions (for example, those of Ar gas) produced by a plasma discharge are accelerated by an electric field and directed to a target (starting material to be vapor-deposited), the atoms in the target surface are flicked out, and the flicked-out atoms are deposited on a semiconductor wafer, yielding a thin film.
In sputtering, however, the species flicked out during the formation of the top electrode film are not limited solely to the atoms that constitute the target, but also include the high-energy electrons present in the plasma region in the vicinity of the target. When these electrons collide with the top electrode film during the formation process, electric charges accumulate on the top electrode film, which is one of the electrodes of an MIM capacitor structure. An electric discharge occurs when the electric charges accumulate beyond the withstand voltage limit of the insulating film on the top electrode film during the formation process. At this point, the insulating film is broken down electrostatically (this type of breakdown will be referred to hereinbelow as an xe2x80x9celectrostatic breakdownxe2x80x9d).
A resulting drawback is that an electrostatically broken-down MIM capacitor structure or a capacitor structure fabricated using this MIM capacitor structure becomes incapable of operating in regular manner.
The present invention was created in order to overcome the above-described drawback of the prior art. An object of the present invention is to provide a method for manufacturing a capacitor structure and a method for manufacturing a capacitor element that allow percent defective to be reduced by controlling the accumulation of electric charges on the top electrode film as a factor that brings about electrostatic breakdown of an insulating film.
A method for manufacturing a capacitor structure in accordance with the present invention comprises the steps of forming a bottom electrode film 21 on a substrate 10, forming an insulating film 22 in the area of the bottom electrode film 21 that excludes a specific area 21a, bringing a grounded conductive member 31 into contact with the specific area 21a of the bottom electrode film 21, forming a top electrode film 23 on the insulating film 22 by performing sputtering such that part thereof is in contact with the specific area 21a of the bottom electrode film 21, and separating the conductive member 31 from the specific area 21a of the bottom electrode film 21.
Another method for manufacturing a capacitor structure in accordance with the present invention comprises the steps of forming a bottom electrode film 51 on a substrate 10, disposing a first clamp ring 61 whose inside diameter is less than the outside diameter of the bottom electrode film 51 above the bottom electrode film 51 in the vicinity of the external periphery thereof, forming an insulating film 52 in an area not covered by the first clamp ring 61 on the bottom electrode film 51, separating the first clamp ring 61 from the upper portion of the bottom electrode film 51, bringing a grounded second clamp ring 62 whose inside diameter is less than the outside diameter of the bottom electrode film 51 but greater than the inside diameter of the first clamp ring 61 into contact with the bottom electrode film 51 in the vicinity of the external periphery thereof, forming a top electrode film 53 on the insulating film 52 by performing sputtering such that part thereof is in contact with the bottom electrode film 51, and separating the second clamp ring 62 from the upper portion of the bottom electrode film 51.
Yet another method for manufacturing a capacitor structure comprises the steps of forming a bottom electrode film 71 on a substrate 10, forming an insulating film 72 on the bottom electrode film 71, bringing a grounded clamp ring 81 whose inner wall is formed substantially perpendicularly to the surface or the substrate 10 or whose inner wall is formed at an incline toward the center of the substrate 10 into contact with the area in the vicinity of the external periphery of an insulating film 72, forming a top electrode film 73 by sputtering on the insulating film 72 and in the upper portion of the clamp ring 81 with the inner wall, and separating the clamp ring 81 from the insulating film 72.
Still another method for manufacturing a capacitor structure in accordance with the present invention comprises the steps of forming a bottom electrode film 91 on the substrate 10, forming an insulating film 92 on the bottom electrode film 91, and forming a top electrode film 93 on the insulating film 92 by performing sputtering in a state in which a member kept at a negative potential is disposed around the substrate 10.
An additional method for manufacturing a capacitor element in accordance with the present invention comprises the steps of forming a capacitor structure on a substrate by any of the manufacturing methods described above, and partially removing the bottom electrode film 21, insulating film 22, and top electrode film 23 constituting the capacitor structure to form a single capacitor element or a plurality of capacitor elements from the remaining bottom electrode film 21, insulating film 22, and top electrode film 23.